The present invention relates to a method to enable a flip-chip type mounting of a chip on a face of a receiver substrate generally constituted by an insulator ceramic associated with conductive tracks. The flip-chip type mounting is known. It results in an assembly wherein the face of the chip containing the contacts of the chip faces the receiver substrate.
There is a known way of carrying out a flip-chip mounting by means of the technique called "ball-bonding" which consists in making electrical links by means of gold wires that have one of their ends melted, for example by means of an electrical arc, to form a small ball. In the case of a chip, this ball is then pressed to a contact of the chip to constitute a pad that is led into contact with the desired position of the receiver substrate on which the chip has to be mounted. It is thus that there is a known way, described in the PCT application No. W0-A-91-00619, of carrying out a soldering, at each contact of a chip, of a gold ball obtained by the melting of the end of a gold wire and then of breaking the wire at a certain distance from the ball. The chip then, at each of its contacts, has a gold ball and a strand of gold wire positioned substantially perpendicularly to the face of the chip bearing the contacts. The chip thus prepared is designed to be mounted on a receiver substrate provided with through-plated holes positioned so that each of them receives one of the gold wire strands that comes into contact with the walls of the through-plated hole into which it is introduced. With a chip prepared in this way, it is very difficult to make the mounting on the receiver substrate since the gold wire strands tend not to remain truly perpendicular to the face bearing the contacts and since it then becomes impossible to introduce them simultaneously into the holes of the substrate receiver.